<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>9.3.JS作用域-作用域链-练习1</title>
    <script>
        // 结果是几？
        function f1() {
            var num = 123;
            function f2() {
                var num = 0;
                console.log(num); //站在目标出发，一层一层往外查找
            }
            f2();
        }
        var num = 456;
        f1(); // 123
    </script>
</head>

<body>

</body>

</html>